Re: [PATCH] amdgpu: add a filter condition when set brightness

[wangyuanzhi]

Hello, I have fixed compilation errors. The lenovo ThinkBook 14 G3 ACL 
notebook bios reports very small brightness value, 3 eg.

On 2023/2/27 22:20, Mario Limonciello wrote:
> On 2/27/23 01:39, Yuanzhi Wang wrote:
> > When the laptop is plugged into AC or DC power supply,
> > the brightness obtained ACPI may be smaller than current
> > brightness.As a result the screen becomes dark，this is
> > not what people want.
>
> Do you have a matching bug report with more information included?
>
> Some relevant details I think we need:
> kernel version
> laptop model
> BIOS version
> if it's the latest BIOS
> some sample numbers that this new warning/behavior catches
> acpidump
>
> At least as described this sounds like a BIOS bug.
>
> > Signed-off-by: Yuanzhi Wang <wangyuanzhi@xxxxxxxxxxxxx>
> > ---
> >   drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c | 9 ++++++++-
> >   1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c 
> > b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> > index d4196fcb85a0..93f1567028c5 100644
> > --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> > +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_acpi.c
> > @@ -406,6 +406,7 @@ static int amdgpu_atif_handler(struct 
> > amdgpu_device *adev,
> >   {
> >       struct amdgpu_atif *atif = &amdgpu_acpi_priv.atif;
> >       int count;
> > +    int old_brightness;
> >       DRM_DEBUG_DRIVER("event, device_class = %s, type = %#x\n",
> >               event->device_class, event->type);
> > @@ -443,7 +444,13 @@ static int amdgpu_atif_handler(struct 
> > amdgpu_device *adev,
> >                    * hardwired to post BACKLIGHT_UPDATE_SYSFS.
> >                    * It probably should accept 'reason' parameter.
> >                    */
> > -                backlight_device_set_brightness(atif->bd, 
> > req.backlight_level);
> > +                old_brightness = backlight_get_brightness(atif->bd);
> > +                if (old_brightness > req.backlight_level)
> > +                    DRM_WARN("old brightness %d is greater than ACPI 
> > brightness
> > +                        %d\n", old_brightness, req.backlight_level);
> > +                else
> > +                    backlight_device_set_brightness(atif->bd,
> > +                        req.backlight_level);
> >               }
> >           }